Date   : Sun, 10 Nov 2002 18:09:50 +0000
From   : Richard_Talbot-Watkins@...
Subject: Re: educational scans/software

Sprow wrote:

> And if you press escape twice the first will say "escape" the second
> "escape at line blah" where blah is the highest line number in the
> program.

Things you never knew about BBC BASIC #1:

The error reporting code in the BASIC ROM is written in BASIC!  If you
search through the ROM, at one point you'll find a bit which is the
tokenised code for:

REPORT:IF ERL PRINT" at line ";ERL:END ELSE PRINT:END

Presumably the reason that a second hit of Escape behaves the way it
does, is that when you hit Escape, the interpreter runs this little
BASIC code fragment, and the second Escape interrupts this normal code
execution, but for whatever reason, the current line number is not set
correctly, and somehow defaults to the last line of the program.

--
Rich Talbot-Watkins
SCEE Cambridge
Richard_Talbot-Watkins@...     




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 SCEE 2002